1. Field of the Invention
The invention relates to a method of removing a metal ion from a treating liquid for use in treating a substrate such as a semiconductor wafer and a glass substrate for use in a liquid crystal display (hereinafter simply referred to as “a substrate”) and to an apparatus for treating a substrate.
2. Description of the Related Art
For example, a conventional type of the apparatus for treating a substrate comprises a treating vessel for storing a treating liquid and receiving the substrate to be treated; a recovery vessel for recovering the treating liquid that overflows from the treating vessel; and a supply piping with which the treating vessel and the recovery vessel are connected and communicated (for example, Japanese Patent No. 2739419).
In the apparatus in such a configuration, the treating liquid can be recycled and reused, so that the amount of the consumed treating liquid can be reduced.
However, the conventional apparatus in such a configuration has a problem as described below.
In the conventional apparatus, metal ions can intrude into the treating liquid and be circulated, so that they can adhere to the substrate and precipitate as the metal on the surface of the substrate.
The apparatus for treating the substrate may have a system in which the treating liquid recovered into the recovery vessel is not circulated but discharged. Even in such an apparatus, the metal ions can intrude into the treating liquid, so that the same problem as described above can be created.